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SubjectRe: [PATCH 1/4] perf pmu: Add function to check if a pmu file exists
Em Wed, May 04, 2022 at 04:02:12PM +0100, German Gomez escreveu:
> Add a utility function perf_pmu__file_exists() to check if a given pmu
> file exists in the sysfs filesystem.

While reviewing this I noticed:

int perf_pmu__caps_parse(struct perf_pmu *pmu)
{
struct stat st;
char caps_path[PATH_MAX];
const char *sysfs = sysfs__mountpoint();
DIR *caps_dir;
struct dirent *evt_ent;
int nr_caps = 0;

if (!sysfs)
return -1;

snprintf(caps_path, PATH_MAX,
"%s" EVENT_SOURCE_DEVICE_PATH "%s/caps", sysfs, pmu->name);

if (stat(caps_path, &st) < 0)
return 0; /* no error if caps does not exist */


------------------------

Shouldn't we introduce a:

const int perf__pmu_pathname_scnprintf(struct perf_pmu *pmu, char *pathname, size_t size, char *filename)
{

return scnprintf(pathname, size, "%s" EVENT_SOURCE_DEVICE_PATH "%s/%s", sysfs, pmu->name, filename);
}

And use in your perf_pmu__file_exists() and in the other places where
this open coded pattern appears?

I'm waiting for reviews for the ARM specific bits.

- Arnaldo

> Signed-off-by: German Gomez <german.gomez@arm.com>
> ---
> tools/perf/util/pmu.c | 17 +++++++++++++++++
> tools/perf/util/pmu.h | 2 ++
> 2 files changed, 19 insertions(+)
>
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index 9a1c7e63e663..9479e9a4da54 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -1854,6 +1854,23 @@ int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt,
> return ret;
> }
>
> +bool perf_pmu__file_exists(struct perf_pmu *pmu, const char *name)
> +{
> + char path[PATH_MAX];
> + struct stat statbuf;
> + const char *sysfs = sysfs__mountpoint();
> +
> + if (!sysfs)
> + return false;
> +
> + snprintf(path, PATH_MAX,
> + "%s" EVENT_SOURCE_DEVICE_PATH "%s/%s", sysfs, pmu->name, name);
> + if (!file_available(path))
> + return false;
> +
> + return stat(path, &statbuf) == 0;
> +}
> +
> static int perf_pmu__new_caps(struct list_head *list, char *name, char *value)
> {
> struct perf_pmu_caps *caps = zalloc(sizeof(*caps));
> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
> index 541889fa9f9c..ab728eaf13b6 100644
> --- a/tools/perf/util/pmu.h
> +++ b/tools/perf/util/pmu.h
> @@ -120,6 +120,8 @@ bool pmu_have_event(const char *pname, const char *name);
>
> int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt, ...) __scanf(3, 4);
>
> +bool perf_pmu__file_exists(struct perf_pmu *pmu, const char *name);
> +
> int perf_pmu__test(void);
>
> struct perf_event_attr *perf_pmu__get_default_config(struct perf_pmu *pmu);
> --
> 2.25.1

--

- Arnaldo

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